Wireless communication has undergone a tremendous development in the last decade. With the evolution and development of wireless networks towards 3 G-and-beyond, packet data services have been the major focus with the aim to provide e.g. higher bandwidth and accessibility to the Internet. Hence, protocols and network architectures including end user devices and terminals are normally designed and built to support Internet Protocol (IP) services as efficiently as possible.
For example, the technique of High Speed Packet Access (HSPA) enhances the Wideband Code Division Multiple Access (WCDMA) specification with High Speed Downlink Packet Access (HSDPA) in the downlink and Enhanced Dedicated Channel (E-DCH) in the uplink. These channels are designed to efficiently support Internet Protocol (IP) based communication by providing enhanced end-user performance and increased system capacity. Though originally designed for interactive and background applications, these channels provide as good or even better performance for conversational services than existing Circuit Switched (CS) bearers.
The E-DCH is a dedicated channel that has been enhanced for IP transmission, as specified in the standardization documents 3GPP TS 25.309 and TS 25.319. The enhancement primarily consists of:                Possibility to use a shorter Transmission Time Interval (TTI)        Use of fast Hybrid Automatic repeat ReQuest (HARQ) between the mobile terminal and the base station. The HARQ mechanism is semi-persistent, as it will abandon a transmission after a fixed number of transmission attempts. The actual number of attempts is determined and signaled from the radio network controller (RNC) to the user equipment (UE) or user terminal.        Scheduling of the transmission rates of mobile terminals from the base station.        
In addition, the E-DCH retains a majority of the features characteristic for dedicated channels in the uplink. Most importantly, as the uplink transmissions are not orthogonal, E-DCH is power controlled in order to avoid creating excessive interference that might make it impossible to detect other user's signals. The power control typically consists of two different mechanisms. First the so-called inner loop power control is performed for each ⅔ time slot. The transmitted power is adjusted so that the measured received signal strength of the Dedicated Physical Control Channel (DPCCH) reaches a predefined signal-to-interference ratio (SIR) target. This target is determined by the so-called outer loop power control, which tries to maintain a consistent block error rate for selected transmission attempts.
One group of conversational services can be referred to as Multimedia Telephone (MMTel). MMTel conversations typically consist of one or more media components, such as voice, video, or text components. The various component types typically have different priority. The voice component is usually considered most important, and thus it is important or even essential to try to preserve good voice quality even at the expense of the video and text components.
When using E-DCH, the interplay of the HARQ and power control can unfortunately result in application level packet losses for two basic reasons. First of all the control delay of the inner loop power control is 2 time slots. This delay is too long for transmission time intervals (TTI: s) of 2 ms duration that only consist of 3 time slots. Consequently, if the required power level changes significantly, the inner loop power control may not be able to adjust the power sufficiently. Second, the outer loop power control gradually lowers the SIR target until a block error occurs. This is problematic for the case of 10 ms TTI, for which the retransmissions take relatively long and thus the maximum number of retransmissions is low. Typically, this interaction with the HARQ and the power control result in the loss of one or a few enhanced Media Access Control (MAC-e) Protocol Data Units (PDU:s).
The loss of one or a few MAC-e PDU:s corresponds to the loss of one or a few application frames. Typically, most applications can recover from a single frame loss, but several consecutive packet losses can result in a noticeable impairment in the media quality.
There is therefore a need for methods and arrangements enabling an improved transmission quality for media transmissions where a packet or frame loss has been detected.